Are there any pianists here who can recommend piano VST's/samples?

I own a MIDI keyboard and I'd like to connect it to PC, because sometimes I need to learn new pieces (or just check out some cool chord progressions) when I'm not able to play my upright piano (e.g. the rest of the family is sleeping). I'd use internal samples of the keyboard, of course, but they sound like a crap... I found a nice piano VST some time ago but unfortunately I don't remember its name.